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INDUSTRIAL AND ENGINEERING CHEMISTRY
VOL. 8, NO. 6
per cent appear to be quite normal. In addition to the volume loss which tends to decrease the over-all fuel economy, an octane depreciation of 2 to 3 units and a general decrease in volatility also result from these losses.
Conclusions
0
FIGURE 8. VAPORLOCKINGCHARACTERIS-
OF SIX REPRESENTATIVE GASOLINES DETERMINATIONS BY VAPOR PRESSURE METHOD
The barometric type of v a POr pressure apparatus h a v i n g a v a r i a b l e vapor volume offers a rapid and /o ’ 2 0 so 3G I & accurate method by which VAPOR T G L I 7 U I D VOLUME RATiG t o d e t e r m i n e the initial vapor pressures of volatile materials. Data of the sort obtained on this apparatus are useful in e s t i m a t i n g evaporation losses and in measuring the vapor-locking charakeristics of gasolines. There are also several other problems, such as the estimation of volatile impurities, for which the apparatus may be useful.
TICS
in Figure 9, it is seen to be free from vapor lock because at 45” c. (113’ F.) less than the limiting quantity of vapor will be formed. However, by projecting the point V / L = 34 and T = 113” F. horizontally to the curve for the gasoline characteristics, it is seen that a quantity of vapor equivalent to V / L = 11.5 is being formed in the fuel system, and since it cannot possibly get through the carburetor jet into the manifold, it must be vented out of the carburetor. This represents a loss in liquid fuel supplied to the engine, equivalent to the amount required to form the quantity of vapor that is vented off from the fuel system, in this case about 6 per cent. That this sort of loss actually occurs in cars has been verified on several occasions when samples were bled from the carburetor bowls of cars while they were running, and the samples compared with the original gasoline supplied to the car. With current model cars operating under approximately normal conditions, losses of as great as 10.8 per cent have been detected and during warm weather losses of 0.5 to 5
Acknowledgment The writers take this opportunity to make acknowledgment
to C. E. Cummings, B. Hegeman, and Keil MacCoull who gave suggestions and advice which were of great assistance in the final development of the apparatus and method.
Literature Cited
,
(5) i6j (7) (8) (9)
Bridgeman, 0. C., S. A . E. Journal, 32, 157 (1933). Chenicek and Whitman, Oil Gas J., 29, 78 (1930). International Critical Tables, Vol. 3, p. 248 (1933). Lipka, “Graphical and Mechanical Computation,” New York, John Wiley & Sons, 1928. MacCoull and Barber. 8. A . E. Journal. 37. 237 (1935). Perry, “Chemical Engineers’ Handbook,” New York, McGrawHill Book Co., 1934. Porter, A. W., Phil. Mag., [7] 17, 711 (1934). Porter, A. W., Phil. Mag. Supplement, [7] 14, 694 (1932). Stauffer, Whitman, and Roberts, ISD. ESG. CHEM.,Anal. Ed., 2, 88-91 (1930)
RECEIVED April 27, 1936. Presented before the Divisions of Gas and Fuel Chemistry, Industrial and Engineering Chemistry, and Petroleum Cbemistry, Symposium on Motor Fuels, at the Qlst Meeting of the Amerioan Chemical Society, Kansas City, Mo., April 13 to 17, 1936.
Laboratory-Scale Ebullition Tube JOHN W. BOEGEL 399 Dupont St., Toronto, Ontario, Canada
A
FTER research work requiring boiling point determinations, for which the method of Siwoloboff was found most suitable, an adaptation of the ebullition tube used in this method proved of value in securing steady boiling of the liquid in a small-scale fractional distillation. The ebullition tube consists of a thin glass rod, long enough to be held upright by resting against the neck of the vessel in which it is used, To the lower end of the rod is sealed a short length (less than 1 em.) of open tube, the diameter of which should be as large as is convenient, 1-em. tubes proving generally useful. For rapid distillation several tubes may be used, while for best results a vacuum distillation requires two or more small-diameter tubes, giving several rapid streams of small bubbles.
This piece of apparatus has proved useful in minimizing bumping in liquids boiled in test tubes, and especially in vacuum distillations, replacing the capillary tube usually used. The capillary must be carefully made, is fragile, is often in need of adjustment, and possesses the further disadvantage of passing air through the hot liquid. After boiling and cooling, the liquid retreats into the open tube, finally filling it. On heating again, the liquid is likely to become superheated ‘until the tube suddenly resumes normal operation with a bad bump. This may be avoided by lifting, draining, and replacing the tube before the second boiling. RECEIVED August 31, 1936.
